U.S. patent number 8,172,843 [Application Number 12/375,265] was granted by the patent office on 2012-05-08 for vertebral fixing system.
This patent grant is currently assigned to Zimmer Spine S.A.S.. Invention is credited to Christian Baccelli, Karl P. Belliard, Keyvan Mazda.
United States Patent |
8,172,843 |
Baccelli , et al. |
May 8, 2012 |
Vertebral fixing system
Abstract
A vertebral fixing system comprising a connecting part with two
longitudinal elements coupled to each other at a first end and
having mutually facing recesses for receiving a rod. A portion of a
flexible ligature extends through orifices of the two longitudinal
elements to define a loop opposite two free ends of the flexible
ligature. The two longitudinal elements are engaged at a second end
of the connecting part via a locking means. When the two
longitudinal elements of the connecting part are locked at the
second end of the connecting part, two strands of the flexible
ligature are pinched between the rod and a wall of the mutually
facing recesses of the two longitudinal elements of the connecting
part, preventing the flexible ligature from moving in translation
relative to the connecting part.
Inventors: |
Baccelli; Christian (Saucats,
FR), Belliard; Karl P. (La Membrolle sur Longuenee,
FR), Mazda; Keyvan (Paris, FR) |
Assignee: |
Zimmer Spine S.A.S. (Bordeaux,
FR)
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Family
ID: |
37654917 |
Appl.
No.: |
12/375,265 |
Filed: |
September 18, 2006 |
PCT
Filed: |
September 18, 2006 |
PCT No.: |
PCT/FR2006/050898 |
371(c)(1),(2),(4) Date: |
March 09, 2009 |
PCT
Pub. No.: |
WO2007/036657 |
PCT
Pub. Date: |
April 05, 2007 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20090326585 A1 |
Dec 31, 2009 |
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Foreign Application Priority Data
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Sep 20, 2005 [FR] |
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05 09570 |
Feb 22, 2006 [FR] |
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06 50609 |
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Current U.S.
Class: |
606/74; 606/324;
606/277; 606/263 |
Current CPC
Class: |
A61B
17/7053 (20130101); A61B 17/707 (20130101); A61B
17/7041 (20130101); A61B 17/7032 (20130101) |
Current International
Class: |
A61B
17/82 (20060101) |
Field of
Search: |
;606/103,139,232,247-279,60,246,74,324 ;623/13.14
;24/132R,132AA,132WL |
References Cited
[Referenced By]
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Primary Examiner: Robert; Eduardo C
Assistant Examiner: Schneider; Lynnsy
Attorney, Agent or Firm: Seager Tufte & Wickhem LLC
Claims
The invention claimed is:
1. A vertebral fixing system, comprising: a connecting part having
two longitudinal elements, wherein the two longitudinal elements
are hinged to each other at a first end of the connecting part,
wherein the two longitudinal elements comprise mutually facing
recesses for receiving a rod there-between, and wherein each of the
two longitudinal elements of the connecting part has an orifice; a
flexible ligature with two free ends, wherein a portion of the
flexible ligature extends through the orifices of the two
longitudinal elements of the connecting part to define a loop
opposite the two free ends; and a locking means for locking the two
longitudinal elements of the connecting part at a second end of the
connecting part, wherein when the two longitudinal elements of the
connecting part are locked at the second end of the connecting
part, two strands of the flexible ligature are pinched between the
rod and a wall of the mutually facing recesses of the two
longitudinal elements of the connecting part, preventing the
flexible ligature from moving in translation relative to the
connecting part.
2. A vertebral fixing system according to claim 1, wherein the
orifices of the two longitudinal elements are in communication with
the mutually facing recesses of the two longitudinal elements.
3. A vertebral fixing system according to claim 1, wherein the
orifices of the two longitudinal elements, in conjunction with a
portion of the mutually facing recesses of the two longitudinal
elements, define a single passage way through which the flexible
ligature is engaged with the connecting part.
4. A vertebral fixing system according to claim 1, wherein when the
two longitudinal elements of the connecting part are not locked at
the second end of the connecting part, the two strands of the
flexible ligature are slidable along a single passageway.
5. A vertebral fixing system according to claim 1, wherein each of
the mutually facing recesses is of substantially semicylindrical
shape.
6. A vertebral fixing system according to claim 1, wherein at least
one of the mutually facing recesses comprises a ruled surface.
7. A vertebral fixing system according to claim 1, wherein the two
longitudinal elements are hinged to each other about a pivot
pin.
8. A vertebral fixing system according to claim 1, wherein the
locking means comprises a head that is engaged in a bore formed in
one of the two longitudinal elements.
9. A vertebral fixing method, comprising: manipulating a portion of
a flexible ligature through orifices of two longitudinal elements
of a connecting part to form a loop opposite two free ends of the
flexible ligature; introducing a rod into mutually facing recesses
of the two longitudinal elements of the connecting part, wherein
two strands of the flexible ligature are disposed between a side
face of the rod and a wall of the mutually facing recesses of the
two longitudinal elements of the connecting part; engaging the two
longitudinal elements of the connecting part; tensioning the
flexible ligature by pulling on the two free ends of the flexible
ligature relative to the connecting part; and locking the two
longitudinal elements of the connecting part to prevent the
flexible ligature from moving in translation relative to the
connecting part.
10. A vertebral fixing method according to claim 9, wherein when
the two longitudinal elements of the connecting part are locked at
a second end of the connecting part, the two strands of the
flexible ligature are pinched between the side face of the rod and
the wall of the mutually facing recesses of the two longitudinal
elements of the connecting part.
11. A vertebral fixing method according to claim 9, further
comprising placing the loop around a bony element.
12. A vertebral fixing method according to claim 9, wherein
tensioning the flexible ligature causes the loop to tighten around
a bony element.
13. A vertebral fixing method according to claim 9, wherein the two
longitudinal elements are coupled to each other at a first end of
the connecting part.
14. A vertebral fixing method according to claim 13, wherein
engaging the two longitudinal elements of the connecting part
further comprises engaging the two longitudinal elements of the
connecting part with a locking means at a second end of the
connecting part.
15. A vertebral fixing method according to claim 14, wherein
locking the two longitudinal elements of the connecting part
further comprises locking the two longitudinal elements of the
connecting part at the second end of the connecting part utilizing
the locking means.
16. A vertebral fixing method according to claim 15, wherein the
locking means comprises a head that is engaged in a bore formed in
one of the two longitudinal elements.
17. A vertebral fixing method according to claim 13, wherein
engaging the two longitudinal elements of the connecting part
further comprises causing ends of the two longitudinal elements of
the connecting part to come progressively closer to each other.
18. A vertebral fixing method according to claim 17, wherein
causing the ends of the two longitudinal elements of the connecting
part to come progressively closer to each other simultaneously
introduces a certain coefficient of friction between the ligature
and respectively the rod and the wall of the mutually facing
recesses of the two longitudinal elements of the connecting
part.
19. A vertebral fixing method according to claim 9, wherein prior
to the locking step, the flexible ligature is slidable relative to
the connecting part.
20. A vertebral fixing method, comprising: manipulating a portion
of a flexible ligature through orifices of two longitudinal
elements of a connecting part to form a loop opposite two free ends
of the flexible ligature, wherein the loop is placed around a bony
element, and wherein the two longitudinal elements are coupled to
each other at a first end of the connecting part; introducing a rod
into mutually facing recesses of the two longitudinal elements of
the connecting part, wherein two strands of the flexible ligature
are disposed between a side face of the rod and a wall of the
mutually facing recesses of the two longitudinal elements of the
connecting part; engaging the two longitudinal elements of the
connecting part at a second end of the connecting part; tensioning
the flexible ligature to fasten the loop around the bony element;
and locking the two longitudinal elements of the connecting part at
the second end of the connecting part, thereby pinching the two
strands of the flexible ligature between the side face of the rod
and the wall of the mutually facing recesses of the two
longitudinal elements of the connecting part.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims foreign priority benefits under 35 U.S.C.
.sctn.119 to International Application No. PCT/FR2006/050898, filed
Sep. 18, 2006, which claims priority to French Application Nos. FR
0650609, filed Feb. 22, 2006, and FR 0509570, filed Sep. 29, 2005.
All applications listed herein are incorporated by reference in
their entireties.
TECHNICAL FIELD OF THE INVENTION
The present invention relates to vertebral fixing system suitable
for being mounted on a vertebra.
An intended field of application is particularly, but not
exclusively, the treatment of scoliosis, or more generally
correcting abnormal curvatures of the spine.
BACKGROUND OF THE RELATED ART
The spine is constituted by superposed vertebrae that are normally
in alignment along a vertical axis, going from the lumbar vertebrae
to the cervical vertebrae, each vertebra presenting a posterior
wall from which there projects a spinous process and two sides
having walls from which there project the ribs and/or transverse
processes. When the spine of an individual presents abnormal
curvature, the vertebrae are inclined relative to one another and
relative to said vertebral axis. The sides of the vertebrae
situated on one side are thus moved closer together forming a
concave side, whereas the sides of the vertebrae on the other side
are spaced apart from one another and form a convex side.
In order to straighten the spinal column, the sides of the
vertebrae on the concave side are spaced apart from one another and
moved relative to one another to distances that are substantially
equivalent to those between the sides of the vertebrae on the other
side. In order to keep the vertebrae in that relative positioning,
known devices have screws that are inserted in the vertebrae or
hooks that are inserted along the inside wall of the vertebral
canal, and rods that are for interconnecting the screws or the
hooks.
The hooks are generally inserted in pairs into each vertebra and on
either side close to the pedicles, with their heads projecting from
the posterior wall of the vertebra, one on either side of the
spinous process. By way of example, the heads form a socket
suitable for receiving a rod that is held in place by means of a
nut screwed onto the head so as to press against the rod. The rows
constituted by the heads of the hooks situated on either side of
the spinous processes are interconnected and held in a fixed
position by two rods that are parallel to each other and to the
axis of the spine.
SUMMARY OF THE INVENTION
Nevertheless, it is difficult to use such hooks since the operator
must under no circumstances interfere with the spinal cord that
extends along the center of the vertebral canal, since otherwise
there is a danger of paralyzing the patient.
The use of screws makes it possible to diminish the risks of the
operation. The screws likewise have socket-forming heads and they
are inserted in pairs into the posterior walls of the vertebrae in
the pedicles on either side of the spinous process. Thus, the
screws constitute points for fixing the vertebrae so as to hold
them relative to one another. Nevertheless, they are necessarily
introduced into the pedicles of the vertebrae, and under certain
circumstances such pedicles can be small in size or damaged.
SUMMARY OF THE INVENTION
The problem that arises and that the present invention seeks to
solve is how to establish fixing points when it is not possible to
introduce screws into the vertebrae in the curved portion of the
spine and when the use of hooks is too dangerous. PCT patent
application WO 2004/010881 in the name of the Applicant describes a
vertebral fixing system that enables the problem to be solved.
That vertebral fixing system adapted to be mounted on a vertebra of
the spine to connect it to a rod comprises: a connecting part
placed facing said rib and/or said transverse process and suitable
for being connected to said rod; an elongate flexible ligature
suitable for connecting together said connecting part and at least
one rib and/or one transverse process; and adjustable locking means
fastened to said connecting part, said ligature having a first end
secured to said connecting part and a free second end suitable for
sliding in said connecting part to form a loop, said locking means
being suitable for holding in a fixed position both said connecting
part relative to said rod, and a length of said ligature between
said ends that is suitable for being prevented from moving in
translation relative to said connecting part by said adjustable
locking means, whereby the loop presents a length that is
determined so as to prevent relative displacement of said rod and
said vertebra in opposite directions.
That system is satisfactory, but under certain circumstances it can
present the following drawback. When the surgeon exerts traction on
the free end of the flexible ligature, the ligature can be jammed
by friction against the bottom face of the process. Under such
circumstances, it will be understood that although the length of
the ligature between the bottom face of the process and the zone
where traction is applied to the ligature is indeed under tension,
the length that extends between the end of the ligature that is
secured to the elongate passageway and the bottom face of the
process is not under tension. Thus, overall, the ligature does not
perform its function of fastening to the vertebra in appropriate
manner.
An object of the present invention is to provide a vertebral fixing
system that enables the above-mentioned drawbacks to be avoided and
that provides controlled locking of the ligature.
According to the invention, to achieve this object, the vertebral
fixing system suitable for being mounted on a vertebra of the spine
in order to connect it to a rod comprises: a connecting part
presenting first and second sides and suitable for being connected
to said rod; a flexible ligature of elongate shape suitable for
connecting together said connecting part and at least one rib
and/or transverse process and/or a portion of the posterior arc of
a vertebra; and adjustable locking means mounted on said connecting
part;
and said system is characterized in that: said ligature presents
two free ends; said connecting part defines at least one passageway
for passing said ligature in such a manner that two distinct
strands of said ligature can be engaged in said passageway(s) so
that said two ligature strands define a first ligature portion
forming a loop that extends from a first side of said connecting
part, and second and third ligature portions extending from the
other side of said connecting part between respective ones of said
ligature strands and said free ends; and said locking means are
distinct from the connecting part and co-operate therewith by
screw-fastening, said locking means being capable of taking a first
position relative to the connecting part in which the two ligature
strands are free in said strand-passing passageway(s), a second
position relative to the connecting part in which the two ligature
strands are prevented from moving in translation relative to the
connecting part, and intermediate positions in which a coefficient
of friction is created between said ligature strands and said
connecting part.
It will be understood that because the two ligature strands that
are on either side of the transverse process are both placed in one
or more passageways, when the locking means are brought into their
locking position, both ligature strands can be used to exert the
tension needed for fixing to the vertebra by means of a rib and/or
a portion of the posterior arc of a vertebra and/or a transverse
process.
In addition, since the locking means co-operate with the connecting
part by screw-fastening, the "dimensions" of the passageways can be
defined accurately during the various stages of clamping and then
locking the ligature.
Preferably, the connecting part defines a single passageway and
both ligature strands are engaged in the single passageway.
Also preferably, the single passageway is defined firstly by the
outside surface of the portion of the rod that is engaged in the
connecting part and secondly by a wall of the connecting part, and
the locking means are suitable for modifying the section of the
passageway.
When the locking means are in their second position, this ensures
effective clamping of the two ligature strands, thereby preventing
them from moving.
In a first embodiment, the connecting part comprises two
longitudinal elements having first ends that are hinged together,
each of said longitudinal elements presenting a recess suitable for
receiving a portion of a section of said rod, a wall of said recess
co-operating with the side surface of said rod to define said
passageway for passing said ligature strands, said locking means
being mounted at the two second ends of said longitudinal
elements.
In a second embodiment, the connecting part comprises a part that
is generally U-shaped, suitable for receiving said rod, and having
the outer ends of the limbs of the U-shape threaded, and the
adjustable locking means comprise a tapped ring suitable for
co-operating with the thread on the U-shaped part, tightening the
ring causing the limbs of the part to be clamped against the
rod.
Preferably, said passageway(s) is/are constituted by the space
between the inside wall of the recess formed in said connecting
part and the side wall of said rod.
BRIEF DESCRIPTION OF THE DRAWINGS
Other characteristics and advantages of the invention appear better
on reading the following description of embodiments of the
invention given by way of non-limiting example. The description
refers to the accompanying figures, in which:
FIG. 1 is a perspective view of a first embodiment of a vertebral
fixing system;
FIGS. 2A, 2B, and 2C are vertical section views of the fixing
system showing the use of said system as shown in FIG. 1;
FIG. 3 is a face view showing the FIG. 1 fixing system put into
place on a vertebra;
FIG. 4 is a perspective view of a second embodiment of the fixing
system, the ligature not being shown;
FIG. 5 is an exploded view of the connection device of FIG. 4;
FIG. 6 is a plan view of a portion of the FIG. 1 connection
device;
FIG. 6A is a section view on line AA of FIG. 6;
FIG. 7 is a face view of the fixing system of the second
embodiment; and
FIGS. 7A and 7B are section views on line VII-VII of FIG. 7 showing
two ways in which the flexible ligature can be put into place.
DETAILED DESCRIPTION
As shown in FIG. 1, in the first embodiment, the vertebral fixing
system comprises a connecting part 12, a flexible ligature 14, and
adjustable locking means 16. The flexible ligature 14 is of
elongate shape and is capable of matching the outline of the parts
it is to connect together. In this figure, there can also be seen
the rod 18 that is to be secured to the vertebra by means of the
vertebral fixing system. In the first embodiment, the connecting
part 12 is constituted by two longitudinal elements given
respective references 20 and 22, each having a first end 22a, 20a
and a second end 22b, 20b.
As can be seen better in FIG. 2A, the longitudinal elements 20 and
22 are hinged to each other at their second ends 20b, 22b about a
pivot pin 24.
In the embodiment described, the locking means are constituted by a
screw 26 having a head 26a that is engaged in a bore 28 formed in
the first end 22a of the longitudinal element 22. The first end 20a
of the longitudinal element 20 is pierced by a tapped bore 28 for
co-operating with the threaded shank 26b of the screw 26. Each
longitudinal element 20, 22 has an outside face 20c, 22c and an
inside face 20d, 22d. The longitudinal elements 20 and 22 are
mounted in such a manner that the inside faces 20d, 22d of the
longitudinal elements face each other. The inside faces 20d, 22d of
the longitudinal elements 20 and 22 have respective mutually-facing
recesses 30 and 32, each of substantially semicylindrical shape.
The recesses 30 and 32 define walls 34 and 36 which are ruled
surfaces having generator lines parallel to the pivot axis 24.
Finally, slots 38 and 40 cause the bottoms of the recesses 30 and
32 to communicate with the outside faces 20c and 22c of the
longitudinal elements 20 and 22. As explained in greater detail
below, the recesses 30 and 32 are for receiving the rod 18 together
with a strand of the ligature 14, the slots 38 and 40 serving to
pass the ligature 14.
With reference to FIGS. 2A to 2C, there follows an explanation of
how the fixing system is used.
In FIG. 2A, there can be seen the longitudinal elements 20 and 22
in the spaced-apart position, a position in which the locking means
16 are naturally not active, the threaded shank 26b of the screw 26
not being engaged in the bore 28. The ligature 14 is engaged in the
slots 38 and 40 of the longitudinal elements against one portion of
the inside wall 34, 36 of the recesses 30 and 32. The rod 18 is
then introduced into the recess 30 of the longitudinal element 20
so that the two strands 42 and 44 of the ligature 14 are disposed
between the inside wall of the recesses 30 and 32 and the side face
18a of the rod 18. These two surfaces define a passageway 46 for
passing the ligature 14 and having the strands 42 and 44 of the
ligature 14 placed therein.
As shown better in FIG. 2B, the strands 42 and 44 of the ligature
define a portion of the ligature 14 that forms a loop 48 that
extends beyond the outside face 20c of the longitudinal element 20,
and also two free portions 50 and 52 that extend beyond the outside
face 22c of the longitudinal element 22. When the longitudinal
elements 20 and 22 are spaced apart as shown in FIG. 2B, the
ligature 14 can slide freely along the passageway 46. Once the
portion 48 of the ligature 14 forming the loop is placed around the
transverse process or a rib or indeed a portion of the posterior
arc of a vertebra, the surgeon engages the threaded shank 26b of
the screw 26 in the tapped bore 28, causing the longitudinal
element 22 to come progressively closer to the longitudinal element
20. This approach simultaneously reduces the section of the
passageway 46 in which the strands 42 and 44 of the ligature are
engaged and simultaneously introduces a certain coefficient of
friction between the ligature and respectively the rod 18 and the
walls of the recesses 30 and 32. Nevertheless, it is still possible
for the surgeon to extract traction on the free ends 50 and 52 of
the ligature 14 until sufficient tension is obtained in the
ligature around the vertebral process. Once the tension in the
ligature is sufficient for providing appropriate fastening, the
surgeon finishes off tightening the screw 26 in the tapped bore 28,
thus locking the longitudinal elements 20 and 22 together.
Simultaneously, it will readily be understood that the strands 42
and 44 of the ligature are pinched between the rod 18 and the wall
of the recesses 30 and 32.
In this locking position, the rod 18 is thus secured to the
ligature 14 via the connecting part 12.
It will also be understood that because the surgeon exerts traction
only on the free ends 50 and 52 of the ligature 14, there is no
risk of jamming between the ligature 14 and the bottom face of the
transverse process or of the rib, thus guaranteeing that effective
fastening is provided with the transverse process or the rib or
indeed a portion of the posterior arc of a vertebra.
This is shown in FIG. 3, where reference AT identifies the
transverse process.
In the above description, both of the strands 42 and 44 of the
ligature are disposed in the recesses 30 and 32 on the same side of
the rod 18. This disposition serves to obtain an optimum result.
Nevertheless, it would not go beyond the invention if the strands
42 and 44 of the ligature 14 were to be placed on opposite sides of
the rod 18. Under such circumstances, it should be considered that
the outside face 18a of the rod 18 and the inside walls of the
recesses 30 and 32 define two passageways, respectively for passing
each of the strands 42 and 44 of the ligature 14.
FIGS. 4 to 7B show a second embodiment of the fixing system.
In these figures, there can be seen the rod 18, the connecting part
now referenced 12', and the flexible ligature 14.
In this embodiment, the connecting part 12' is constituted by a
part 50 that is generally U-shaped. The inside wall of this part is
constituted by a bottom 52 of substantially semicylindrical shape
and by two substantially plane portions 54 and 56 that correspond
to the two limbs of the part 50. The width l of the recess 58
formed in the part 50 is substantially equal to the diameter d of
the rod 18. On its outside face 50a which is circularly symmetrical
about a longitudinal axis of the part 50, there is provided a
thread 60 occupying its upper portion. The thread 60 is located
entirely above the rod 18 when it is put into place in the recess
58. The thread 60 is designed to co-operate with a clamping ring 62
that constitutes the adjustable locking means. This ring has a
slightly frustoconical bore 64 with an inside face 66 that carries
tapping 68.
It can thus be understood that when the ring 62 is screwed tight on
the threaded portion 60 of the part 50, it deforms the limbs of the
part 50 elastically, thereby pinching and clamping strands of the
ligature 14 between the rod 18 and the inside wall(s) of the recess
58, in a manner explained below.
As shown better in FIGS. 6 and 6A, the part 50 includes in its
bottom 70 a passage 72 for passing the ligature 14 in a manner
explained below.
With reference to FIGS. 7, 7A, and 7B, there follows a description
of two different ways of putting the flexible ligature 14 into
place inside the connecting part 12' in the second embodiment. The
side wall of the rod 18 and the inside wall of the recess 58 of the
part 50 potentially define two passageways 74 and 76 for passing
the middle strands of the flexible ligature 14. In the
configuration shown in FIG. 7A, only the passageway 74 is used.
Thus, both intermediate strands 42 and 44 of the flexible ligature
14 are disposed in the passage 74. This disposition presents all of
the advantages described with reference to the first
embodiment.
In the configuration shown in FIG. 7B, the middle strands 42 and 44
of the flexible ligature 14 are disposed respectively one in each
of the passageways 76 and 78, i.e. on either side of the rod 18.
This configuration likewise presents all of the advantages
described with reference to the first embodiment of the device
since the free ends 50 and 52 of the ligature 14 are accessible for
exerting the desired traction in order to obtain suitable clamping
on the spinous process prior to locking the clamping ring 62 on the
part 52.
This second embodiment presents the advantage of being simpler in
design since it serves in particular to avoid making two
longitudinal parts constituting a kind of clamp hinged on the pin
24.
It will be understood that in both embodiments, the locking means
are constituted by an element that is distinct from the connecting
part and that is removable therefrom. In addition, in both cases,
the locking means co-operate with the connecting part by screw
engagement. It is thus possible to adjust accurately the dimensions
of the ligature-passing passageway(s) as defined by the connecting
part and the rod. In an initial stage, the coefficient of friction
between the coefficient of the ligature and secondly the rod and
the connecting part can be adjusted. In the final stage, very
effective clamping of the ligature is obtained between the rod and
the locking part.
* * * * *